2014+ AFM (Active Fuel Management)

Colossus · November 8, 2014

I must be in the minority when I don't like aftermarket exhaust systems.

Coach Hill · December 15, 2014

Yeah AFM! Didn't like it so I tuned it out. Can't tell that I'm getting any worse mileage since tuning. Not sure you can convince me that a 6,000 lb vehicle running on 4 cylinders is going to save fuel! By the way, I like my truck a LOT better now that it shifts like it should and I'm getting more of the engine's potential.

WendysOrBust · December 29, 2014

Not sure you can convince me that a 6,000 lb vehicle running on 4 cylinders is going to save fuel!

Its not that hard. Under certain circumstances only a fraction of the engines power is required to keep the vehicle in constant motion. The bread and butter of the AFM is on the highway going 50-65mph, which is the average speed limit of US highways. At those speeds is where the truck is most aerodynamic and when the v4 can keep the truck at a consistent speed.

It is really hard work to get a 6000lb truck to get over 20mpg. That is why things like the air dam, tires, and ride stance or so important and sensitive at the same time. Just take a look over at the suspension/leveling thread. When guys level their trucks and remove the air dam and add larger tires they can take a hit of up to 4mpg.

KARNUT · December 29, 2014

Its not that hard. Under certain circumstances only a fraction of the engines power is required to keep the vehicle in constant motion. The bread and butter of the AFM is on the highway going 50-65mph, which is the average speed limit of US highways. At those speeds is where the truck is most aerodynamic and when the v4 can keep the truck at a consistent speed.

It is really hard work to get a 6000lb truck to get over 20mpg. That is why things like the air dam, tires, and ride stance or so important and sensitive at the same time. Just take a look over at the suspension/leveling thread. When guys level their trucks and remove the air dam and add larger tires they can take a hit of up to 4mpg.

I turned mine back on twice no change in gas mileage that was noticeable. It did vibrate at slow speeds and made that awful V4 drone.

WendysOrBust · December 29, 2014

I turned mine back on twice no change in gas mileage that was noticeable. It did vibrate at slow speeds and made that awful V4 drone.

Well what kind of driving where you doing? What mpg where you averaging with AFM and without. Like I said above. AFM might only net you .5mpg during city driving. Its during highway speeds where it nets you 2-3mpg. I've averaged full tank 20.5 mpg's while driving down to Houston but usually get 17.5 with a 50/50 City/Highway mix. Now these past few tanks I've been running e85 which causes AFM to run longer and more frequently, however my mpg's have dropped to 15 with mostly highway and down to 13ish with city and highway mix.

If you have an aftermarket exhaust I can see disabling it since it'll sound like a "helicopter" with certain exhaust combinations. But as far as just daily driving I can't even tell when its on. I have to specifically change my info screen in my gauge cluster to be aware that its coming on/off.

For me its never caused any vibrations or a laggy throttle. From what I've read before it only activates and stays running when engine load is under 10%.

Edited December 29, 2014 by WendysOrBust

WendysOrBust · December 29, 2014

edit: double post

Edited December 29, 2014 by WendysOrBust

KARNUT · December 29, 2014

Well what kind of driving where you doing? What mpg where you averaging with AFM and without. Like I said above. AFM might only net you .5mpg during city driving. Its during highway speeds where it nets you 2-3mpg. I've averaged full tank 20.5 mpg's while driving down to Houston but usually get 17.5 with a 50/50 City/Highway mix. Now these past few tanks I've been running e85 which causes AFM to run longer and more frequently, however my mpg's have dropped to 15 with mostly highway and down to 13ish with city and highway mix.

If you have an aftermarket exhaust I can see disabling it since it'll sound like a "helicopter" with certain exhaust combinations. But as far as just daily driving I can't even tell when its on. I have to specifically change my info screen in my gauge cluster to be aware that its coming on/off.

For me its never caused any vibrations or a laggy throttle. From what I've read before it only activates and stays running when engine load is under 10%.

Mine would come on in town in fourth gear and vibrate and drone. As far as HWY on a trip east on I10 past Lake Charles and average 22MPG at 72 MPH with it off. Earlier with less miles on it and a stock muffler I got 19MPG going north from Conroe to Buffalo at 75 MPH with it on. Just recently before my last service I turned it back on and added back the muffler the drone and the vibration was gone but the mileage didn't change. When its time for the next service I will try it again. I did notice the transmission seems happier at low speed shifts with it off, less confused. Notice the same when I had it on but driving in M5 in town, less confusion with the shifts.

Gmcant33 · January 7, 2015

For me it's a fun video game seeing how much time I can spend in V4. My best so far is accelerating from 15 all the way to 50 on just 4 cylinders. My instantaneous readout usually goes up about 20% when it changes from V8 to V4, so it does save some gas. With a small lift and 34" tires, 20mpg overall seems pretty good to me.

Is this on e85? Or 87 nice numbers btw

DanielAcosta · January 9, 2015

Is this on e85? Or 87 nice numbers btw

Mostly 87, occasionally 85 in parts of the country that sell it.

Edited January 9, 2015 by DanielAcosta

Silverado-Hareek · January 9, 2015

I haven't been following this entire thread but I have recently started driving around town in M5 to keep it in V8. The truck feels MUCH better now. I may consider getting the Range AFM delete device if I can find the funds. I dont' want to tune the truck while it's under warranty. But I'm keeping it in M5 at all times unless I'm on the interstate.

Edited January 9, 2015 by Silverado-Hareek

glcbn · January 10, 2015

It's been pretty cold here lately, and I've noticed the truck goes into V4 more often and when it does, it stays there longer. But in this cold, mileage has taken a dive. The colder the worse it is too. It struggles to get to the mid 17's. Right before fall set in I was working on 22 average. For mileage, seems these engines prefer warm temps.

Silverado-Hareek · January 12, 2015

It's been pretty cold here lately, and I've noticed the truck goes into V4 more often and when it does, it stays there longer. But in this cold, mileage has taken a dive. The colder the worse it is too. It struggles to get to the mid 17's. Right before fall set in I was working on 22 average. For mileage, seems these engines prefer warm temps.

I've experienced the opposite. Before I started driving in mostly M5, I noticed the truck stayed in V8 mostly until the engine warmed up and then it would switch to V4 accordingly.

Chad2815 · February 15, 2015

Anyone else noticed V4 doesn't come on until the engine hits 210? Would be curious to see if a lower thermostat would cause issues because of this.

calgator73 · February 16, 2015

Mine comes on well before that. Think v4 is a function of a few things. Leave the house it's 18°F. When the needle moves off the peg the hvac starts blowing warm and pretty soon after that v4 (maybe 180 at the latest)